BPSK Audio Modem

GNU Radio study.

Posted by WT on August 9, 2019

Foreword

Recently, I found an interesting GNU Radio flow graph and post that flow graph on my blog. This is the source of this flow graph. It was made by Dr. Aaron Scher. You can also download this file here.

Flow graph

BPSK Audio Modem Flow Graph (both transmitter and receiver are in the same flow graph).

BPSK Audio Modem Flow Graph

Operation step

  1. Set up a simple client to listen to port 9989. I do this with my mac by opening up a new Terminal window and using the nc (or ncat) utility:
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nc -l 9989
  1. Execute the flow graph in GNU Radio Companion.

  2. (Quickly) Set up a simple server to connect to 127.0.0.1 port 1234 I do this with my mac by opening up another Terminal window and using the nc utility:

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nc 127.0.0.1 1234
  1. If everything works (sometimes you need to try the above methods a few times before it works - not sure why), you should be able to send text message from the server terminal to the client terminal by sound. Here is a demo:

Demo: BPSK audio modem with GNU Radio.